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International audience; In aeronautics, the issue of ice shedding prediction is of prime importance in the assessment of electro-thermal ice protection systems. In this paper, an ice shedding mechanism based on pressure redistribution in the water film formed at the ice/airfoil interface is proposed. This pressure distribution induces a stress concentration that leads to crack propagation in the ice. To determine whether this mechanism is relevant or not, two numerical experiments are performed. The results of these numerical experiments and the influence of a few material parameters are discussed, as well as their limitations and possible consequences arising from some of the hypotheses.The numerical modeling is based on recent works on damage/fracture mechanics which provide a general framework for fracture mechanics computation. The effects of numerical parameters and mesh size are discussed. A mixed mode test case based on experimental data is also performed. This test casehad not been attempted before on this particular numerical method, which therefore serves as further validation.

This paper treats the blast response of a pile foundation in saturated sand using explicit nonlinear finite element analysis, considering complex material behavior of soil and soil–pile interaction. Blast wave propagation in the soil is studied and the horizontal deformation of pile and effective stresses in the pile are presented. Results indicate that the upper part of the pile to be vulnerable and the pile response decays with distance from the explosive. The findings of this research provide valuable information on the effects of underground explosions on pile foundation and will guide future development, validation and application of computer models. Accepted version

This paper presents a new algorithm to simulate theseismic responseofN-story building frames incorporating friction energydissipators; a device per floor is considered. The frames with the dissipators are described by 2Dlumped masses modelswith twodegrees of freedomper floor, namely the horizontal displacements of the main structure and of the dissipators. The proposed algorithm consists of a modification of thelinear accelerationmethod; the main innovation consists of checking at each calculation instant the sliding or sticking condition at each floor, hence, the number of “active” degrees of freedom changes continuously, ranging in betweenN(there is sticking condition at every dissipator) and 2N(there is sliding condition at every dissipator). Some results given by this algorithm are compared to experimental results fromad-hoc testingand to numerical results obtained with the ADINA software package. In both cases, agreement is satisfactory while the proposed method is more computationally efficient.

This paper is concerned with an accurate prediction of the effects of adjacent structures on the blast loads on a building in urban terrain. Blast loadings on structures have typically been evaluated using empirical relationships. These relationships assume that there are no obstacles between the charge and the target. In real situations, the actual blast loads can either be reduced due to shadowing by other buildings or can be enhanced due to the presence of other buildings in the vicinity. Results of the numerical simulations presented in this study for multiple buildings in an urban environment have demonstrated the importance of accounting for adjacent structures when determining the blast loads on buildings. An approach to determining the enhancement factors is described.

Tailored welded blanks allow the combination of different materials and different sheet thicknesses in a single blank, thus letting designers and engineers to fit, in initial blank, local needs of strength or other demands in the stamped component. The selection of the best material combination for a part involves a high number of parameters associated with the technologies used in industry. Sheet metal forming technology is widely used to obtain different type of parts. In these processes a large amount of plastic deformation is generally imposed to the sheet. The complexity of the plastic deformation has lead to the development of numerous techniques to predict or evaluate the formability of the raw materials. In the last few years, important developments have been achieved, based on new theoretical models and experimental validation. In this paper two experimental benchmarks are used to evaluate the ability of tailored welded blanks in the drawing process. In addition, the numerical simulation of such examples was performed and the comparison with experimental results is also presented.

In this paper, we consider the simulation of microelectromechanical structures (MEMS). The objective of this work is to develop reliable numerical procedures that will help improve our understanding of MEMS behaviors, and enable optimal design of MEMS. A hybrid FEM-BEM method is developed to solve the coupled electrostatics and mechanics equations. Sensitivity analysis is carried out using the direct differentiation approach (DDA) to compute the design sensitivity coefficients (DSCs). The DSCs can then be used to drive optimization procedures. The numerical approaches are validated on a simple MEMS device—the tungsten microtweezer. The nonlinearity of the electrostatic force is found to dominate the behavior of this device. Sensitivity analysis and optimization procedures are used to compute critical parameters related to the nonlinear behaviors, as well as to solve inverse problems. The nonlinear behaviors of the tweezer are explained using a simple physical analog which is found to exhibit many of the same behaviors. Quantitative comparisons of the simulated results with experiments are also presented.